The invention relates to novel polymers derived from poly(arylcyclobutene) monomers.
The polymeric compositions of this invention are useful in films, as molded articles, in coatings, as adhesives, and in composites.
In recent years the search for high-performance materials, especially high-temperature-resistance polymers, has gained momentum. In order for a material to be useful at high temperatures, it must fulfill several requirements including a high melting or softening temperature, a high modulus or rigidity at elevated temperature, a resistance to solvent and chemical degradation, and toughness. The intrinsic thermal and oxidative stability of aromatic structures has long been recognized, and a variety of polymers have been made in which benzene rings are linked together by various connecting groups. Among the more stable aromatic polymers that fulfill the requirements of high-temperature resistance are the polybenzimidazoles, the polybenzoxazoles, polyimides, and some polyamides, such as the polyaramides. Of these polymers, the polyimides have had the most interest.
The major difficulty encountered in the commercial development of these materials is that they are usually obtained in the form of a powder which cannot be readily fabricated into useful objects.
The polyimides prepared from aliphatic diamines and aromatic dianhydrides are generally soluble and thermoplastic. Aliphatic polyimides have been prepared from bis(dienophiles) and a diene such as a bis-diene. In many cases, such reactions proceed with the evolution of gases and other volatile components.
Aromatic polyimides, such as polypyromellitimides, have a spectrum of superior properties. These polyimides may be prepared by the reaction of an aromatic dianhydride with an aromatic diamine to give a soluble polyamic acid, which on cyclodehydration gives the insoluble desired product.
High performance plastics reduce the weight of mechanical components, and not just by virtue of their densities. Their high performance properties allow greater design stresses, and often elements can be downsized accordingly. In recent years, aromatic polyimides have become widely accepted as premium, high performance engineering plastics. These resins are well known for having excellent properties at elevated temperatures (i.e., chemical resistance and mechanical strength) but are also costly. Historically, polyimide resins are difficult to fabricate into objects other than fiber and films. The most common methods of manufacturing parts having high strength and temperature properties are hot compression-molding, machining from hot-compression, and molded or extruded rod). Given the synthetic and fabrication difficulties, a new route to polyimides and other high performance plastics is desirable.
Many thermally polymerizable compounds are prepared from monomers which have a poor shelf-life and are unstable in the presence of oxygen or oxygen-containing gases. Further, many processes for the polymerization of thermally polymerizable compounds result in the generation of volatile components, which can create problems in the product such as the creation of voids in molded articles. Further, the removal of such volatile by-products can create problems. Also, many of such polymerization processes require the use of curing agents, initiators or catalysts. The use of such curing agents, initiators or catalysts often results in polymers which contain impurities which may effect the final properties.
Polymers which polymerize through thermal mechanisms; wherein such mechanisms which do not require the use of catalysts, initiators or curing agents; and which do not form volatile by-products, are needed. Polymers derived from monomers which polymerize by thermal mechanisms, wherein such monomers have a good stability, shelf-life, and are stable in the presence of oxygen, are desirable. Polymers formed by thermal polymerization mechanisms, with a good modulus, which are thermally stable, which have low water pickup, are reasonably hard and are insoluble, are needed.